Abstract: Taking the dropping ludrjcaing oil of the three phase electric transformer of l00KVA as an example,to use flexibly the theory and method of the threephase electric transformer’s short crcuit test may add 380V affernating current directly to the high voltage winding of the transfomer and utilize the windings copper consumption to dry the electric transformer.This method is simple,safe and reliable,and it can save time and work and bring remarkable economic benefits.